The top flowers look ok but could be improved with a slight amount of translucence and a very small bump map in the displacement slot. You could also look at the specularity and add small amounts in there. If you have an image editor open the petal texture and turn it in to a greyscale and try varying levels of contrast and lightness/darkness and use those images in the spec, translucence and displacement.The bottom flowers look like they have the wrong mapping or possibly the wrong image so check that and work on their spec, translucence and displacement as well.Good luck :)